Screenshot only works for visible area

[uuf6429]

This seems to be a known limitation of Electron.

Potential solution:

• create browser windows with some special settings:

  options.x = 0;
  options.y = 0;
  options.enableLargerThanScreen = true;

• find content size (document.body.scroll<S>)
• resize the window (content size + window.outer<S> - window.inner<S>)
• take screenshot
• resize back to original size

Some tentative code:

                Logger.debug('getScreenshot()');

                screenshotResponse = null;

                currWindow.webContents
                    .executeJavaScript('({' +
                        'cw: document.body.clientWidth,' +
                        'ch: document.body.clientHeight,' +
                        'pw: window.outerWidth - window.innerWidth,' +
                        'ph: window.outerHeight - window.innerHeight' +
                    '})', false, function (s) {
                        const scaleFactor = Electron.screen.getPrimaryDisplay().scaleFactor,
                            origSize = currWindow.getSize();

                        Logger.alert('Setting window size to %dx%d...', s.cw + s.pw, s.ch + s.ph);
                        currWindow.setSize(s.cw + s.pw, s.ch + s.ph, false);
                        Logger.alert('Window size is now: %j', currWindow.getSize());

                        const tryTakingScreenshot = function (tries) {
                            currWindow.capturePage(
                                /*{
                                    x: 0,
                                    y: 0,
                                    width: +s.cw * scaleFactor,
                                    height: +s.ch * scaleFactor
                                },*/
                                function (image) {
                                    const data = image.toPNG().toString('base64');

                                    if (data) {
                                        screenshotResponse = {'base64data': data};
                                        currWindow.setSize(origSize[0], origSize[1], false);
                                    } else if (tries > 0) {
                                        Logger.warn('Failed to take screen shot, trying again (try %d).', tries);
                                        setTimeout(function () {
                                            tryTakingScreenshot(tries - 1);
                                        }, 200);
                                    } else {
                                        screenshotResponse = {'error': 'Gave up trying to take screen shot after several tries.'};
                                        currWindow.setSize(origSize[0], origSize[1], false);
                                    }
                                }
                            );
                        };

                        tryTakingScreenshot(5);
                    });

                cb();

Also see: https://github.com/FWeinb/electron-screenshot-app/blob/6c165089797d30ad66a0b19398ca52446e0d3e88/index.js